New focusing lens system and tolerance analysis for near-field recording system

Tolerance analysis for focusing unit of near field recording system is presented. The assembling and manufacturing tolerances of SIL and OL are simulated using CODE V. In addition, we proposed to move collimated lens (CL) back and forth to compensate and control these tolerances, especially in optical axis direction. And we proposed, a new doublet solid immersion lens (DSIL) for near field optical system, which can minimize the tilting, decenter, defocus misalignment problems between objective lens and solid immersion lens in existing near field optical system. The objective lens, which confines the beam, and secondary lens which increases the numerical aperture, join together to make one module cemented lens system.